In many production line situations, such as in manufacturing or testing situations, it is required to load objects such as containers into cavities in holders therefor, and subsequently to unload them from the holders. In comparison to merely transferring such objects from one conveyor to another, this loading in particular requires relatively precise positioning of the object such that it is deposited accurately into its cavity in its respective holder. This is all the more important when the object is fragile, such as e.g. in the case of glass syringes, since they must be handled and deposited gently to avoid breakage. Such holders are used as caddies to transport the objects through at least part of the manufacturing and/or testing system, and are commonly known in the field of leak testing as “pucks”. It should be noted that these holders thus do not form part of the consumer product being manufactured or tested, rather are used to assist in the holding and transport of the objects through at least part of the manufacturing or testing system, the objects themselves constituting at least part of the end product.
Typically, this is achieved by using a robot to transfer the objects into the holders by collecting each object from a conveyor individually and depositing it as gently as required in its respective holder, before returning to collect another object and repeat the process. Unloading the objects from the holders is performed in the reverse sequence. Modern robots are fast enough to perform these tasks even when the container holders are provided in a continuously-moving stream. However these processes are still relatively slow, and depending on the geometry of the loading arrangement, are limited to loading and unloading about 60 objects per minute. Furthermore, the movement of the robot is typically jerky, exhibiting high accelerations, which risks damaging the objects if they are fragile.
FIG. 1 illustrates schematically such a prior art robot-based apparatus for loading objects into holders. Holders 10 provided with cavities 17 are conveyed sequentially in a stream on a conveyor mechanism 11, which may be of any known type such as linear, curved, or rotary. Objects 12, which may be of any type or shape, are conveyed along an object input conveyor 13, from which they are collected one-by-one by grippers 16 of a robot arm 14 of a robot 15. These grippers 16 may be of any known type such as pincers, hooks, one or more suckers, or similar. The robot arm 14 is movable both parallel and perpendicular to the plane of conveyor mechanism 11, so as to deposit objects 12 into respective cavities 17. After depositing an object 12 in the cavity of a holder 10, the robot returns to collect another object 12 from the object input conveyor 13, and the process repeats. If the holders 10 are moving continuously, the robot arm 14 follows this movement in synchronicity therewith, and the grippers 16 release the objects 12 either when they have reached their final insertion depth in the holders 10, or just before such that the object 12 falls a short distance into its resting place in its respective holder 10.
Unloading objects 12 from container holders 10 is carried out by an essentially mirror-image apparatus with the same components but operated in reverse. In the interests of conciseness, such a prior art arrangement need not be described further.
When utilising such a robot-based system, the only way to increase the throughput is, besides accelerating operation of the one robot, to use multiple robots, which is expensive and entails high maintenance costs and increased risk of parts breakage.
An object of the invention is thus to overcome the above-mentioned disadvantages of the prior art and thereby to provide apparatuses and methods for loading and unloading objects from cavities in holders at a significantly greater rate than possible with prior art methods and apparatuses, thereby minimising acceleration forces exerted upon the objects.
The invention also concerns the application of these methods and apparatuses to a method of manufacturing closed, unleaky containers, and an apparatus for leak testing containers respectively.